Car safety features can be active or passive. Active ones enable the driver to better control the car thus avoiding accidents and passive ones help to protect the drivers and passengers in a crash.
Active safety features include a well designed dashboard, easy to reach controls, good all round visibility and anti - lock braking systems (ABS). See this How Stuff Works article to find out more about ABS. Also stability control, as now recommended by the EU New Car Assessment Programme on car safety.
Passive safety features work in the event of a crash by slowing down the impact. As two cars hit each other their crumple zones collapse slowly ensuring that the force of impact is transferred to the people in the car over a longer period of time than if the cars had hit and then bounced off each other like two snooker balls. The safety cage protects the driver and passengers and their seatbelts stretch slightly in the event of a crash. This gives them more time in which to restrain the wearer and so causing the driver and passengers less damage.